Linear ball bearing

ABSTRACT

A linear ball bearing having a guide carriage ( 2 ) which is guided on a guide rail ( 1 ) in a longitudinally displaceable manner and is mounted in rolling contact on longitudinal sides of the guide rail ( 1 ) via balls ( 3 ) which are arranged on each longitudinal side in at least two parallel ball rows ( 4, 5 ) encircling in endless ball channels ( 6 ), each ball ( 3 ) of the one ball row ( 5 ) together with an adjacent ball ( 3 ) of the other ball row ( 4 ) being held all round in cage pockets ( 8 ) of a common cage piece ( 7 ), the cage piece ( 7 ) having exactly two cage pockets ( 8 ) for one ball ( 3 ) each from both ball rows ( 4, 5 ), each cage piece ( 7 ), as viewed in the running direction of the balls ( 3 ), being provided at both ends with convexly curved end surfaces ( 9 ) for contact with the end surfaces ( 9 ) of adjacent cage pieces ( 7 ), which end surfaces ( 9 ) extend essentially up to the cage piece sides ( 10 ).

The present invention relates to a linear ball bearing having a guidecarriage which is guided on a guide rail in a longitudinallydisplaceable manner.

DE 26 18 535 A1, for example, has disclosed a linear ball bearing havinga guide carriage which is guided on a guide rail in a longitudinallydisplaceable manner and is mounted in rolling contact on longitudinalsides of the guide rail via balls. The balls are arranged on eachlongitudinal side in at least two parallel ball rows encircling inendless ball channels. All the balls are held in cage pieces. A total offour balls are held all round in a cage piece, to be precise two ballsof the one row and two balls of the other row. In order to eliminatepossible distortion forces, provision is made for the cage pieces to beof elastic design in the running direction or for them to be providedwith elastic means. End surfaces, touching one another, of cage piecesadjacent to one another extend only over part of the width of the cagepieces in order to avoid deformations on lobes which enclose the balls.If these lobes are deformed under undesirable contact, jamming of theballs may occur. The fact that the end surfaces, touching one another,of the cage pieces, as viewed transversely to the running direction,extend only over a small part of the width of the cage piece encouragesundesirable tilting of this cage piece. However, in these known linearball bearings, tilting is prevented by virtue of the fact that two ballseach of both ball rows, that is to say a total of four balls, aremounted in a common cage piece. A disadvantage with this known cage,however, is that, on account of the considerable extent of the cagepiece which is required in the running direction, tight deflecting radiiin the deflecting region of the linear ball bearing can only be overcomewith difficulty.

The object of the present invention is therefore to specify a linearball bearing according to the features of the precharacterizing clauseof claim 1 in which this disadvantage is removed. According to theinvention, this object is achieved in that the cage piece has exactlytwo cage pockets for one ball each from both ball rows, that is to sayfor exactly one pair of balls of both ball rows, each cage piece, asviewed in the running direction of the balls, being provided at bothends with convexly curved end surfaces for contact with the end surfacesof adjacent cage pieces, which end surfaces extend essentially up to thecage piece sides.

The invention dispenses with spring elements, as are required in theprior art. With the invention, very tight deflecting radii for the cagepieces are possible, since the cage pieces require only a smallconstruction space as viewed in the running direction of the balls. Thefact that one ball each of both ball rows is arranged in a common cagepiece would encourage lateral tilting of the cage pieces without furthermeasures. However, the end surfaces extending according to the inventionup to the cage piece sides prevent the risk of lateral tilting of thecage pieces.

The two cage pockets of the cage piece are preferably connected to oneanother in one piece by a web whose web sides facing away from oneanother and arranged essentially parallel to the running direction ofthe balls are provided with contact surfaces for guiding the cage pieceon guide surfaces of the guide carriage. In this developed linear ballbearing according to the invention, the risk of tilting of the cagepiece is even further reduced. The web sides provided with the contactsurfaces can be guided satisfactorily on the guide surfaces of the guidecarriage. The movement of the balls through the endless ball channels issatisfactorily ensured overall, tight deflecting radii for the cagepieces being possible with the linear ball bearing according to theinvention.

The end surfaces of the cage pieces preferably have a partly cylindricalprofile, the cylinder axis of which is arranged transversely to therunning direction of the balls and parallel to a plane in which the twoball rows on the longitudinal side lie.

The invention is explained in more detail below with reference to anexemplary embodiment shown in a total of six figures. In the drawing:

FIG. 1 shows a linear ball bearing according to the invention in partialsection,

FIG. 1 a shows a detail of the linear ball bearing from FIG. 1,

FIG. 2 shows the linear ball bearing according to the invention in aside view,

FIG. 3 shows a cage piece of the linear ball bearing according to theinvention according to FIGS. 1 and 2 as a detail,

FIG. 4 shows the cage piece from FIG. 3, but with inserted balls, and

FIG. 5 shows a plurality of cage pieces arranged one behind the otherwith inserted balls.

FIGS. 1, 1 a and 2 show a linear ball bearing according to the inventionin sectional view and in side view. A guide carriage 2 is supported in alongitudinally displaceable manner on a guide rail 1 via balls 3. Theguide carriage 2 contains a total of four encircling ball rows 4 and 5.Of the latter, only two ball rows 4 and 5 on one side are shown insection. The ball row 4 is the top row, whereas the ball row 5 is thebottom row. The guide carriage 2 shown in FIG. 2 is of symmetricalconstruction. The guide rail 1, on which the guide carriage 2 isdisplaceable in the axial direction, is designed as a profile rail. Thedisplacement is made possible by the rolling of the balls 3 on the guiderail 1 and the guide carriage 2.

During the axial displacement, the balls 3 run in the guide carriage 2in endless ball channels 6. When the guide carriage 2 is beingdisplaced, the balls 3, in a design without spacers, could strikeagainst one another and thus cause noise. To prevent such noisegeneration, the balls 3 are separated from one another by cage pieces 7.

Each ball 3 of the one ball row 4 forms a pair with an adjacent ball 3of the other ball row 5, and this pair is held all round in cage pockets8 of a common cage piece 7. The cage pockets 8 enclose the balls 3 inthe shape of a spherical indentation. The cage piece 7 has exactly twocage pockets 8 for exactly one pair of balls 3 of both ball rows 4, 5.As viewed in the running direction of the balls 3, each cage piece 7 isprovided at both ends with convexly curved end surfaces 9 for contactwith the end surfaces 9 of adjacent cage pieces 7. The end surfaces 9extend essentially up to the cage piece sides 10; lateral tilting of thecage pieces 7 is avoided, since the one cage piece 7 can be supported onthe adjacent cage piece 7 in contact with the end surfaces 9. In otherwords, the end surfaces 9 in this case extend over the entire width ofthe cage piece 7. The cage piece 7 is depicted especially clearly inperspective illustrations in FIGS. 3 and 4.

The two cage pockets 8 of the cage piece 7 are connected to one anotherin one piece by a flat web 11. Web sides facing away from one anotherand arranged essentially parallel to the running direction of the ball 3are provided with contact surfaces 12, 13 for guiding the cage piece 7on guide surfaces 14, 15, 16, 17 of the guide carriage 2. FIG. 1 a showsa detail of the linear ball bearing according to the invention fromFIG. 1. A leg 18 of the guide carriage 2 can be seen in this figure. Theguide surfaces 15, 16 are formed directly on the leg 18. The guidesurface 14 is formed on a wire 21 which is fastened to the ends of theguide carriage 2. The guide surface 17 is formed on a cover 19.

The end surfaces 9 of the cage piece 7 have a partly cylindricalprofile, the cylinder axis of which is arranged transversely to therunning direction of the balls 3 and parallel to a plane in which thetwo ball rows of a longitudinal side lie. End surfaces 9, touching oneanother, of cage pieces 7 adjacent to one another, can satisfactorilyroll on one another, even in the case of tight deflecting radii, withoutthere being the risk of canting or of lateral escape.

It can clearly be seen in FIG. 4 that the cage pockets 8 enclose theballs 3 all round.

FIG. 5 shows a plurality of cage pieces 7 arranged one behind the other,the end surfaces 9 of which are touching one another. The flat webs 11together form an endless web band 20.

LIST OF ITEM NUMBERS

-   1 Guide rail-   2 Guide carriage-   3 Ball-   4 Ball row-   5 Ball row-   6 Ball channel-   7 Cage piece-   8 Cage pocket-   9 End surface-   10 Cage piece side-   11 Web-   12 Contact surface-   13 Contact surface-   14 Guide surface-   15 Guide surface-   16 Guide surface-   17 Guide surface-   18 Leg-   19 Cover-   20 Web band-   21 Wire

1. A linear ball bearing having a guide carriage (2) which is guided ona guide rail (1) in a longitudinally displaceable manner and is mountedin rolling contact on longitudinal sides of the guide rail (1) via balls(3) which are arranged on each longitudinal side in at least twoparallel ball rows (4, 5) encircling in endless ball channels (6), eachball (3) of the one ball row (5) together with an adjacent ball (3) ofthe other ball row (4) being held all round in cage pockets (8) of acommon cage piece (7), characterized in that the cage piece (7) hasexactly two cage pockets (8) for one ball (3) each from both ball rows(4, 5), each cage piece (7), as viewed in the running direction of theballs (3), being provided at both ends with convexly curved end surfaces(9) for contact with the end surfaces (9) of adjacent cage pieces (7),which end surfaces (9) extend essentially up to the cage piece sides(10).
 2. The linear ball bearing as claimed in claim 1, in which the twocage pockets (8) of the cage piece (7) are connected to one another inone piece by a web (11) whose web sides facing away from one another andarranged essentially parallel to the running direction of the balls (3)are provided with contact surfaces (12, 13) for guiding the cage piece(7) on guide surfaces (14, 15, 16, 17) of the guide carriage (2).
 3. Thelinear ball bearing as claimed in claim 1, in which the end surfaces (9)have a partly cylindrical profile, the cylinder axis of which isarranged transversely to the running direction of the balls (3) andparallel to a plane in which the two ball rows (4, 5) of a longitudinalside lie.